W4.1_Lower GI Therapeutics Flashcards
1
Q
What are the definition and categorisations of diarrhoea (3)? What is the pathophysiology of diarrhoea (4)? What are the causes of diarrhoea (5)?
A
- More frequent and loose stools than usual (change in bowel habit)
- Bristol Stool Chart: type 5, 6, 7
- Acute: <14 days Persistent: 14-28 days Chronic: >28 days (a sign of underlying problem)
- Pathophysiology: increased osmotic load in gut lumen, increased secretion, inflammation of intestinal lining, increased intestinal motility (less time to reabsorb water)
- Causes: infection (bacteria/virus), ingestion of toxins, drugs, parasites, anxiety (most are self-limiting and resolved within 72 hours)
2
Q
What is travellers diarrhoea? What are the characteristics and causes of it? What are the prevention methods of travellers diarrhoea?
A
- Experienced by travellers/holiday makers (destination? age? diet?)
- Early onset (within first few days of trip), ≈acute diarrhoea but can have dysentery
- Some infections can cause persistent/recurrent diarrhoea or systemic complications
- Causes: E. Coli, Campylobacter, Salmonella, viruses…
- Prevention: hygiene/food/drink advice, rarely recommend antibiotic prophylaxis
3
Q
What is chronic diarrhoea? What are the causes of it (5)?
A
- Recurrent/persistent diarrhoea
- Causes: IBS, IBD, malabsorption (coeliac), metabolic diseases (diabetes, hyperthyroidism), laxative abuse
4
Q
What are the symptoms (6), diagnosis methods, and (moderate) dehydration signs of acute diarrhoea (4/5)?
A
- Symptoms: loose/liquid stools, increased frequency, abdominal cramping, flatulence, mild abdominal tenderness, rapid onset
- Diagnosis: stool frequency, nature, occurrence, duration, onset, timing, diet/food, travel, meds
- Dehydration signs: tiredness, nausea, light-headed, anorexia
- Moderate dehydration signs: dry mouth, sunken eyes, decreased urine output, feeling thirsty, decreased skin turgor (through pinch test)
5
Q
State the red flags for diarrhoea.
A
- > 3 days in healthy adults, >2 days in elderly, >1 day in diabetic patients
- Associated with severe vomiting/fever
- Recent travel to tropical/subtropical climate
- Blood/mucus in stool
- History of change in bowel habit (>40yo)
- Severe pain/rectal pain
- Suspected ADR
- Alternating diarrhoea and constipation in elderly (faecal impaction)
- Unexplained weight loss
- Recent hospital treatment/antibiotic treatment (C. diff.?)
- Evidence of dehydration/unable to drink fluids
- Steatorrhoea (fatty, looser, smellier, paler, floating stool)
6
Q
What is the main suggestion and primary aim in treatment for diarrhoea? Explain the treatment guidelines in terms of first-line treatment, general management, and medication history.
A
- Stay at home, rest, let it ‘run its course’
- Primary aim to prevent dehydration and re-establish normal fluid balance
- First line treatment: oral rehydration therapy/solution (ORT/ORS)
- Contain sodium and potassium to replace essential ions, citrate/bicarbonate to correct acidosis, glucose (or other carbohydrates) -> sachets dissolved in water (200-400mL), diabetic patients have to monitor blood glucose level carefully
- General management: plenty of clear fluids, avoid sugary drinks, avoid milk/dairy, eat light/easily digested food, hygiene precautions required for gastroenteritis
- Medication history should be checked + advise as diarrhoea may reduce absorption
7
Q
When are pharmacological intervention needed for diarrhoea? What are the medications used (5)?
A
- Alter gut motility, staying at home/resting is impractical/inconvenient
- Loperamide: more reabsorption of water & electrolytes
+ increase tone of anal sphincter to reduce faecal incontinence/urgency - Low dose morphine: direct action to slow down contraction of intestinal smooth muscle
- Diphenoxylate: synthetic derivative of pethidine, sold as co-phenotrope (with atropine)
- Adsorbents: adsorb microbial toxins/micro-organisms (ex. Kaolin, Bismuth subsalicylate)
- Antibiotics: stool sample should be taken and causative organism identified before prescribing
8
Q
In terms of loperamide, explain its drug action, metabolism, contra-indications, cautions, side effects, and toxicity.
A
- Loperamide: µ-opioid receptor agonist -> direct action on opiate receptors in gut wall to reduce propulsive peristalsis -> longer intestinal transit time -> more reabsorption of water & electrolytes
+ increase tone of anal sphincter to reduce faecal incontinence/urgency - Extensive first-pass metabolism causes little reaches systemic circulation to prevent opioid effects
- Contra-indications: active ulcerative colitis, antibiotic associated colitis, conditions where inhibition of peristalsis should be avoided, abdominal distension develops
- Avoid: bloody/suspected inflammatory diarrhoea, significant abdominal pain
- Side effects: abdominal cramps, dizziness
- MHRA: severe cardiac ADR in very high doses
9
Q
What is the definition of constipation? What are its pathophysiology and causes?
A
- Unsatisfactory defecation due to infrequent stools/difficult stool passage/seemingly incomplete defecation
- <3 bowel movements per week, more common in pregnant and elderly, type 1/2 Bristol Stool Chart
- Pathophysiology: increased water reabsorption in large intestine leads to harder stools that are more difficult to pass (due to increased intestinal transit time of food or ignoring of defecation reflex)
- Causes: functional (idiopathic) or secondary (induced by conditions/medicine)
10
Q
Explain the non-medical (4), medical, and medicinal factors (7) of constipation. What are symptoms (6) and diagnositic methods of constipation?
A
- Non-medical factors: inadequate fluid/dietary fibre intake, dieting, lifestyle change, suppressing urge to defecate
- Medical conditions: coeliac, depression, diabetes, GI obstruction, IBS, Parkinson’s, hypercalcaemia, hypokalaemia, hypothyroidism
- Medications: antacids, antihypertensives, antidepressants, antimuscarinics, antiparkinsonian medicines, opioid analgesics, iron
- Symptoms: abdominal discomfort and distension, abdominal cramping, bloating, nausea, difficulty passing stool, specks of blood due to straining (bright red)
- Diagnosis: usual bowel habit, frequency and appearance, nature, occurrence, pain, duration, onset, diet/food, travel history, medication/medical history
11
Q
What are the red flags for constipation?
A
- Unexplained weight loss
- Blood in stools
- Rectal bleeding
- Family history of colon cancer/IBD
- Signs of obstruction
- Nausea/vomiting/abdominal pain
- > 40 yo without any cause in bowel habit change
- > 14 days duration
- Tiredness
- Alternating with diarrhoea to suspect IBS
- Pain on defecation that cause suppression of defecation reflex
12
Q
What is the treatment aim for constipation? What are the non-pharmacological treatments for constipation?
A
- Treatment aim: restore normal frequency, achieve regular/comfortable defecation, avoid laxative dependence, relieve discomfort
- Non-pharmacological: consider primary cause (ex. diet, increased fluid intake, lifestyle/exercise)
13
Q
Regarding pharmacological interventions for constipation, laxatives would be the main option. Explain the formulation, mechanism, patient advice, and examples of bulk-forming laxatives.
A
- Formulation: granules, effervescent granules
- Mechanism: increase faecal mass through water-binding -> formulate bulky soft stool -> stimulate peristalsis
- Patient advice: maintain good fluid intake, onset of 1-3 days, can be used in for long term, dilute with enough water, don’t take at bedtime
- ex. Ispaghula Husk/Fybogel, Methylcellulose
14
Q
Explain the formulation, mechanism, patient advice, and examples of stimulant laxatives.
A
- Formulation: G/R tablets, oral solution, oral suspension, suppositories
- Mechanism: irritate nerve cells in intestines -> increase intestinal motility through muscle contractions + promote water influx to intestine to promote bowel movement
- Patient advice: only for >18yo, avoid prolonged/overuse as it can cause fluid/electrolyte disturbances, onset of 6-12 hours, can cause abdominal cramps, take at bedtime
- ex. Bisacodyl, Senna, Sodium picosulfate, Co-danthramer
15
Q
Explain the formulation, mechanism, patient advice, and examples of osmotic laxatives.
A
- Formulation: oral solution, powder, enema, suppositories
- Mechanism: draw water into faeces via osmosis -> increase stool volume and softens -> stretches wall of intestines to trigger defecation reflex
- Patient advice: maintain good fluid intake, check for allergy (lactose/galactose), possible abdominal pain/flatulence/bloating, macrogol powders/lactulose take days to work vs phosphate take minutes vs magnesium hydroxide take hours
- ex. Lactulose, Macrogol, Sodium citrate, Phosphate, Magnesium hydroxide
